1. Field
One embodiment of the present invention relates to a multilayer printed circuit board that restricts EMI, and a design method of a multilayer printed circuit board.
2. Description of the Related Art
When an IC mounted on a printed circuit board operates, EMI is emitted from the IC and wiring connected to the IC. When a magnitude of EMI is larger than a certain value (for CISPR regulation [10 m method], 30 dBμV/m in a frequency range up to 230 MHz, and 37 dBμV/m in a frequency range of 230 MHz to 1 GHz), EMI is over the standard, and products cannot be shipped.
In order to restrict EMI, there has been disclosed a technique of providing a ground pattern around a multilayer printed circuit board so that ground surfaces in different layers are connected with each other (Jpn. Pat. Appln. KOKAI Publication No. 2005-340733).
In recent years, an amount of generated EMI tends to be large, and development of a technique of restricting EMI has been desired.